Snap on pad and insulator



July 28, 1964 SNAP 0N PAD AND L. J- STERN INSULATOR Original Filed June 11, 1957 INVENTOR tEW/S d 5 TEE/V ATTORNEY United States Patent 3,142,073 SNAP ON PAD AND INSULATOR Lewis J. Stern, Adrian, Mich., assignor to Stubnitz Greene Corporation, Adrian, Mich., a corporation of Michigan Original application June 11, 1957, Ser. No. 664,947, now Patent No. 2,985,230, dated May 23, 1961. Divided and this application Jan. 23, 1961, Ser. No. 84,366

1 Claim. (Cl. -354) The present invention relates to improvements in pads particularly adapted for use in the trimming of spring structures of vehicle seats, furniture and the like, and the method of making the same, being a division of my application Serial No. 664,947, filed June 11, 1957, now Patent Number 2,985,230, granted May 23, 1961.

It has been the practice in the past, in connection with the upholstering of a vehicle seat, for example, to use an insulating strip disposed directly over the top of the spring elements defining the resilient supporting structure of the seat. The function of this insulating strip was to protect the pad material disposed above the spring elements from the abrading action of the spring elements and to distribute the support of the spring elements over the entire area of the pad material and avoid the possibility of the outline of the spring elements being felt by a person sitting upon the upholstered seat. One form of insulating strip of the type just described is shown in Patent No. 2,218,749 in which the strip consists of a suitable fabric, such as burlap, having lengths of reinforcing wire threaded therethrough.

Also, it has been the practice for some time to use pads of molded foam rubber in connection with the upholstery of vehicle seats and the like, as shown in Patent No. 2,783,827. More recently such pads have been fabricated from polyester-urethane and polyether-urethane foams. The function of such molded foam pads has been to mask the spring elements and to provide comfort and feel to the upholstered seat or cushion.

According to the present invention it is proposed to substitute for known forms of pad and insulator strips, an improved seat pad construction in which a molded reaction material has associated therewith, as an integral bonded part, an insulator pad or strip. In carrying out the invention, 1 have provided an improved method whereby the foam material is molded with the insulator pad or strip in place and the foam pad and insulator strip are bonded together as an integral laminated unit.

Preferably my improved integral pad and insulator strip is molded with retaining grooves to enable the pad to be snapped over the top border frame of the spring structure with the elimination of other known forms of attachment structure for such pads, as for example hog rings and the like, for retaining the pad in position before apnplying the final trim. Preferably the material of the insulating strip is disposed within the retaining grooves of the pad to reinforce that area.

The insulating strip material to be integrally molded in the pad may be burlap, cotton, linen, felt, jute, paper, sisal or other suitable material in woven or so-called weftless form. The insulator strip may also be formed of string, cord, rope, Wire net or screening. Moreover, the insulator strip may comprise chopped fibers such as glass fibers, of different length, roving and the like, blown or otherwise positioned within the mold and then molded into position.

If woven or meshed material is used for the integral insulator strip, it is possible to vary the physical properties of the insulator strip, as claimed in my application Serial No. 664,947, by means of slits cut in the strip either before or after molding. These slits may be either transverse or longitudinal in direction depending upon the final properties desired. When chopped fibrous material is used for the insulator strip, the physical properties thereof may be varied by controlling the location and orientation of the strands or by slitting the molded chopped fibers in longitudinal, transverse or angular directions.

It is also within the scope of the present invention to mold the pad and then bond the insulator strip to the pad as a separate operation. Moreover, it is contemplated that the pad and insulator strip may be molded together and the resulting pad may have a further pad portion applied thereto. For example, a pad portion of polyester-urethane foam material may be integrally attached to a burlap insulating strip as one operation and, thereafter, the resulting pad may have applied to its upper surface a pad section of polyether-urethane foam material.

Thus, the object of the invention is to provide an improved snap-on pad for spring structures.

This and other objects and advantages of the invention will more fully appear from the following description an the appended claims.

In the drawings,

FIG. 1 is a diagrammatic cross-sectional showing of my improved pad supported upon spring elements,

FIG. 2 is an enlarged view of a detail shown in FIG. 1,

FIG. 3 is an enlarged fragmentary perspective view of a pad showing the insulator strip of slitted form,

FIG. 4 is a diagrammatic sectional view of a mold for carrying out the method of the invention, and

FIG. 5 is a fragmentary view similar to FIG. 1 showing a pad of sectional foamed structure.

In the illustrated form of the invention shown in FIGS. 1 and 2, the molded foam pad 10 has a retaining groove 12 adapted to receive the upper border frame 14 of the spring structure 16. Located atthe underside of the pad 10 in a position to engage directly with the spring structure 16 is an insulator strip 18 which is suitably bonded or otherwise integrally associated with the surface of the pad 10 which is engaged by the spring elements 20.

In practice, the strip 18 may be of lightweight woven burlap or cotton canvas. When the strip 18 is to be molded integrally with the pad 10, the strip 18 may be placed in a suitable mold 22, as shown in FIG. 4. By making the mold 22 in the manner shown, the strip 18 may be clamped in position within the mold and, thereafter, when the reaction material 24 is placed in the mold and the chemical foaming action takes place to fill the mold 22 the reaction material penetrates the interstices of the strip 18 to integrally bond the same to the pad 10 upon curing the material within the mold in a well known manner. Upon removing the pad 10 from the mold, the strip 18 may be severed to provide slits 25. FIG. 5 shows a pad 10 having a very soft upper part 26 of foamed material and a lower part 28 of a somewhat more firm foamed material, the latter being bonded to the insulator strip 18'. The upper part 26 may be separately formed and then bonded to the part 28 or it may be foamed and cured on the lower part 28 as a separate operation from the foaming and curing of the lower part 28. It will be understood that any suitable bonding or adhesive material compatible with the foam reaction material may be employed to secure the sections 26 and 28 together or to attach the insulator strips 18 and 18' in position where they are not integrally bonded by. impregnation of foamed material taking place in the mold itself.

The reaction material which is preferably formed and cured in bonding relation to the insulating strip ma terial 18 and 18' may take several forms depending upon the results desired. Using polyester-urethane foams, for a 25% deflection, a compression resistance in the range of 0.8 to 1.2 pounds per square inch has been obtained. With polyether-urethane foams, for a 25 deflection, a compression resistance in the range of 0.2 to 0.5 pound per square inch has been obtained. To insulate against the feel of the spring structure 16, the polyester type foams permit the use of relatively thin pads. However, the insulating strip 18 reduces the thickness and density requirements of the foam layer or layers of the pad and contributes to the economy of the composite seat construction. It also increases the serviceability of the foam material making up the main body of the pad 10. 1 An example of a suitable type of polyester foam folows:

Parts by weight Resin 100.0 Emulsifier 1.0 to 2.0 Catalyst 0.1 to 2.0 Water 1.5 to 4.0 Diisocyanate 20.0 to 55.0

In the above example, the resin would be saturated polyester resin having a low acid number, preferably less than 2.0 and a hydroxyl number of 60 plus or minus 15. The emulsifier may be anionic or a mixture of anionic and a non-ionic detergent. The catalyst is a tertiary amine and preferably N-methyl morpholine. The water may be distilled or deionized or mere tap water although preferably it is distilled or deionized. The diisocyanate is an isomeric mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate of which the ratio of isomers lies between 65 and 80 parts of the 2,4-isomer to 35 and of the 2,6-isomer. The 80-20 isomeric mixture is preferable wherein the 80 parts is the 2,4-isomer.

A specific formula used in practice and falling within the above example is:

Parts by weight Resin 100.0 Witco 77-86 2.0 N-methyl morpholine 1.0 Water 3.0 Hylene TM 43.0

wherein Hylene TM comprises 80 parts 2,4-tolylene diisocyanate and 20 parts 2,6-tolylene diisocyanate.

The specific formula set forth immediately above may be used in providing the cellular reaction product of the present invention either in a straight-shot method or in a prepolymer system. In the straight-shot system, the resin and all other ingredients except the diisocyanate are mixed together and this mixture as one component is mixed with a diisocyanate to produce the foam. In the prepolymer system, the diisocyanate and a part of the resin are pre-reacted to form polymer in which all hydroxyl groups in the resin are converted to urethane groups by using a large excess of diisocyanate. Thus, all the functional groups of the prepolymer are isocyanate. This prepolymer is then used as one of the components and the second component consists of additional resin, emulsifier, catalyst and water. For example, the first component may consist of resin 50 parts by weight and diisocyanate 43 parts by weight and the second com- 4 ponent may consist of resin 50 parts by weight, emulsifier 2 parts by weight, catalyst one part by weight and water 3 parts by Weight. The reaction of the first and second components produces the foam.

An example of a suitable type of polyether-urethane foam follows: The polyether foams involve the prepolymer system only. The usual practice is to combine the resin with an excess of diisocyanate to form the prepolymer. The isocyanate groups which are not reacted in the formation of the prepolymer are free to react with water in producing the foam. In like manner, such free isocyanate groups may react with other materials containing active hydrogen compounds, e.g., burlap, cotton, etc. For example, the block polymer Tetronic 701 which is a condensate of ethylene oxide, propylene oxide and ethylene diamine is cooked with tolylene diisocyanate (:20 isomer mixture). The resulting resin is converted to a foam by mixing with an emulstfier, catalyst and water. A typical formulation is as follows:

Prepolymer: Parts by weight Tetronic 701 100.0 Hylene TM 34.8

Cook two hours at F. to form prepolymer.

Foam formulation: Parts by Weight Prepolymer 100.0 DC-200 (50 centistokes) 0.5 N-methyl morpholine 1.0 Water 2.8 Triethylamine 0.2

The prepolymer may consist of a mixture of polymers including such resins as Pluronics, Polypropylene glycol, Teracol, etc. Usually the mixed polymers are mixed together and then cooked with diisocyanate rather than involving separate cooks with subsequent mixing.

Preferably the insulator strip is bonded to the cellular reaction product in the mold during the foaming action with the result that the physical characteristics of the insulator strip are improved by the impregnation of the foam material and the chemical reaction taking place between the reaction material and the insulator strip.

An important feature of the present invention resides in the concept of a resilient pad having a depending peripheral flange with a recess defined therein adapted to receive the upper border wire of the spring structure, the resilient character of the pad enabling the same to be snapped upon the upper border frame.

In connection with the method of forming a laminated cellular reaction product especially designed for use as a pad, it is to be understood that the foam is allowed to expand against the insulating sheet of burlap or other fabric making up the insulator strip and the foam penetrates the porous fabric material becoming mechanically bonded thereto. As a result the fabric is stiffened. In addition, reaction of free diisocyanate in the foaming product with reactive groups in the fibrous material of the fabric (principally hydroxyl groups) vulcanizes the foamed reaction product to the fabric. This reaction results in further stiffening the fabric sheet and converts it into an excellent insulating strip bonded to the resilient cellular pad body and provides excellent high tear and abrasion resistance.

I claim:

A molded pad of resilient urethane foam for use on a spring structure having an upper border frame, said pad having a top portion for disposal upon the top of the spring structure, an integral peripheral flange portion on the underside of said top portion and depending normal therefrom in an unstressed state to dispose the same along the sides of the spring structure, said flange on the inside thereof being formed with an undercut wall portion to provide an area of maximum clearance directly adjacent the underside of said top portion, an insulator extending along said underside of said top portion with its edges disposed on the inside of said flange and extending into said area of maximum clearance so as to reinforce said wall portion, the inside dimensions of said flange below said area being less than the inside dimensions of said area and the inside dimensions of said area being less than the peripheral outside dimensions of the border frame with said flange unstressed whereby said flange may be snapped on the border frame and the top portion retained in position on the spring structure with the border frame located in said area of maximum clearance with said insulator being located between the border frame and said wall portion, the resiliency of said top portion and flange constituting the retaining means for holding the pad upon the spring structure.

References Cited in the file of this patent UNITED STATES PATENTS Becher Feb. 2, Toms Feb. 12, Neely Mar. 5, Meyers July 30, Haussling Oct. 28,

FOREIGN PATENTS Germany Oct. 23, Great Britain Aug. 29, France June 16, Great Britain Feb. 29, Great Britain July 3, 

